I have
friends who love to match their cars in quarter-mile races (legally, of
course), and to squeeze every bit of horsepower out of their engines,
they even add nitrous oxide. While the result is a neck-snapping, lift-off-like
jolt, this temporary enhancement is just not a practice conducive to long
engine life.

Boat
owners are not likely to compete in quarter-mile increments hoping to
beat 12 seconds, but like their automobile-enthusiast counterparts, many
of them do want to get more horsepower out of their powerplants. Fortunately,
most prefer to leave that job to professionals: the people who manufacture
marine diesels. But how does an engine manufacturer take an existing engine
and increase its output without making major changes like increasing the
displacement and still manage to maintain engine durability? Caterpillar
recently completed an 18-month enhancement project to its 660-hp 3196,
creating the 700-hp C-12, and it agreed to explain to me just how it added
horses.

There
are many ways to increase horsepower in an engine. Which method engineers
select is at least partly dependant upon the size of the increase they're
looking for. In this project, the increase was considered modest, according
to Tryg Tow, project engineer for the Marine Product Engineering Power
Systems Marketing Division of Caterpillar. So to achieve the 40-hp boost,
Caterpillar started by addressing the 3196's air intake system.

The
first step was a new turbocharger that would pump more air into the cylinders.
Tow says that Caterpillar polled its suppliers and discovered a higher
efficiency turbocharger that fit perfectly. "We leveraged off that,"
he says, by lowering exhaust manifold restriction.